The apertures of the radiating elements for these missions are of the order of 2.5 to 3.5 times the emission wavelength. This means that the use of cones having high surface efficiencies for these applications should be avoided, given their bulk at these radiating aperture sizes.
One alternative solution is to create an array of metal radiating elements having smaller apertures in order to take advantage of their small heights and of their very high surface efficiencies. To this end, it is then necessary to produce a power divider that supplies the access points of these metal elements in phase and with low losses. This divider has to be compact so as not to modify the gain in compactness afforded by using sources having smaller apertures.
Moreover, according to needs, this divider must also be able to operate:                in bipolarization with isolation between the two polarizations of greater than 20 dB;        over relatively large frequency ranges;        in circular polarization;        at moderate or high power levels.        
The use of propagation lines on a PCB, an acronym for Printed Circuit Board, of microstrip or strip line type is an appealing option for obtaining a highly compact divider. However, this approach is handicapped by the transmission losses that it causes and the low power levels that it allows.
The option of using metal guides, for its part, allows transmission losses to be minimized and high power levels to be supported. However, for its part, it is penalized by the bulk of the metal guides. Divider architectures have been proposed for obtaining compact dividers with this technology. French patent FR 3 012 917, entitled ‘Répartiteur de puissance compact bipolarisation, réseau de plusieurs répartiteurs, élément rayonnant compact et antenne plane comportant un tel répartiteur’ (Compact bipolarization power divider, array of a plurality of dividers, compact radiating element and plane antenna comprising such a divider) describes a dual-polarization plane power divider comprising at least four asymmetrical orthomode transducers, known as OMT, linked in an array and able to be coupled in-phase to a dual orthogonal polarization power source by way of two power distributors connected perpendicularly to one another. In another configuration, the excitation assembly is formed of a single symmetrical OMT connected to two dividers each having two output ports arranged such that the difference in electrical length between the two outputs is equal to a half wavelength of the emission signal.
These various solutions make it possible to achieve compact devices operating in bipolarization, in spite of the use of metal guides. However, their bandwidths are not enough to address the wide bandwidths required for the active antenna applications of telecommunications satellites in the Ku band and in the Ka band.